getting closer to solving bogging down problem

Merc 2 stroke 150hp V6 1982: this engine has been bogging down to about 1,300rpm at WOT. I rebuilt the fuel pump, replaced tank and line to the engine, using 89 octane new gas. Laddies suggested that I check the spark on each plug, but I don't know how to do that at WOT, so I haven't done it yet. This weekend, I shot an entire can of Deep Creep into the carbs. After it sat for 20min, I fired her up and she went for about 20 min (this should have long burned off the Deep Creep, right?) at over 4,000rpm and then bogged back down out of the blue while I was still holding her at WOT. I repeated the same thing with another can of Deep Creep and she responded the same exact way. What could possibly be cleared up with Deep Creep in the carbs and then reappear after 20min of good riding? Do I have 2 issues...maybe an underlying electronic issue that kicks in intermittantly after I address the initial carb cleanliness with Deep Creep? Can bad coils cause this?

Re: getting closer to solving bogging down problem

The only way I know to conveniently check the spark at WOT is with the use of a SmarTach meter. It can be clipped onto a spark plug wire while the motor is running at WOT and the meter shows the level of secondary voltage in the wire. It works like magic (perhaps induction?). I have one and got it used on eBay for 1/2 price of retail.

If Deep Creep is really having a 20 minute effect on the running of the motor, I would guess that it is affecting the rings and compression on the cylinders temporarily. You don't mention if you did a compression check, so I would do that to see if low compression might be part of the problem.

Good luck